Preparation of a photochromic ink
AssigneeBASF SE
InventorsMarc Maurer, Max Hügin, Thomas Raimann, Leonhard Feiler, Bruno Inderbitzin, André Fuchs
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Abstract
The present invention relates to a photochromic ink, the process for its preparation which is based on a spiropyran powder obtainable by melting, cooling and crushing, and to a new form of a spiropyran obtainable thereby. Said process to prepare a photochromic ink comprises the steps of a) heating and melting the spiropyran at a temperature below 250 C, b) cooling the melt to obtain a solidified spiropyran, c) crushing the solidified spiropyran to obtain a powder, d) optionally adding the powder to a binder providing the basis for the photochromic ink.
Claims10
A process to prepare a photochromic ink comprising the steps of
- a) heating and melting the spiropyran at a temperature below 250° C.,
- b) cooling the melt to obtain a solidified spiropyran,
- c) crushing the solidified spiropyran to obtain a powder, and
- d) adding the powder to a binder providing the basis for the photochromic ink.
A photochromic spiropyran in the form of a powder which, after dispersion in a printing ink, has at least the double color strength than known forms of the same spiropyran, said powder being obtainable by
- a) carefully heating a photochromic spiropyran until it has melted,
- b) cooling the melt to obtain a solidified spiropyran, and
- c) crushing the solidified spiropyran to obtain a powder.
Dependencies are inferred from the claim text.